#include <iostream>

using namespace std;

int main()
{
    int a = 5;
    decltype(a) b = a;
    b = 10;
    cout << "a:" << a <<endl;
    cout << "b:" << b <<endl;
    decltype((a)) c = a;
    c = 20;
    cout << "a:" << a <<endl;
    cout << "c:" << c <<endl;
}